Process for threading nuts.



A. K. LOVELL. PROUESI: FOR THREADING NUTS.

APPLICATION FILED JAN. 11, 1912.

Patented Oct. 20, 1914.

[NIENTUR Jlerf UNITED STATES OFFICE.

ALBERT K. LOVELL, on NEW HAVEN, CONNECTICUT.

' PROCESS FOR THREADING NUTS.

ting the thread by means of a suitable tap or cutting tool revolved within the 'nut blank, and thereby removing the material of the blank to form the groove which makes the thread. The said process is slow and expensive, especially in tapping the smaller sizes of 'nuts which involves the breakage of the small and highly tempered tools required. It is further objectionable in that it abrades to some extent the surface of the thread, particularly its edge or exterior angle.

My process contemplates the direct and complete formation of the thread by means of exterior compression of the nut blank around and upon a threaded former, and compacting and elongating the molecules of the stock without removal or waste of the materials, thereby producing a tougher and superior thread, with smoothed and hard-- ened surface.

In the accompanying drawings forming a part of this specification, Figure '1 is a vertical cross section of the punch holder of the usual commercial power press used in machine shops, and a thread former and compression die for carrying out my'improved process for threading nuts, with a nut blank 5 in position for operation. Fig. 2 is a similar view with the parts in the position of a later stage in the process with the nut threaded, and ready for removal from the former. Fig. 3 is a plan view of the die used for carrying out this improved process. Fig. t is a plan view of a nut blank prior to compression, and Fig. 5 is a similar view of a finished nut, after removal from the compression die.

thread former.

- In carrying out my improved process for threading nuts, any ordinary suitable form of power press may be employed, here re- Specification of Letters Patent.

Fig. 6 is an end view of the Patented Oct. 20, 1914.

Application filed January 11, 1912. Serial No. 670,720.

quiring no description, nor illustration except its relation to the special appliances i for forming the nut threads, for which pur pose the punch holder or vertically reciproeating gate is shown, and designated by the numeral 1 on the. drawings. Said nut threading appliances comprise in their simplest form a thread former 2 the shank 3 of 'which is received and held in a socket 4 in the lower end of the gate, 1, and a compression die 5 which is bolted or otherwise secured to the die bed 6, which as usual is bolted to the bed of the press A'here denoted by the broken sectional shading shown but requiring no further description or delineation.

The thread former 2, below its shank 3 is v of cross sectional form of the transverse eonfiguration of the finished nut, that is, square 3 or hexagonal, as the case may be, and of somewhat slightly less area, as shown in Fig.

2. Below said part, is a central cylindrical,

conically pointed teat or part- 7, screw 1 threaded to conform to the required threads of the nut, and resembling a pointed bolt in external appearance, as shown. Said screw threaded teat is hardened to the degree usual for taps and similar cutting tools, and the base of the former, above the teat or I shoulder at the junction of the two parts is correspondingly hardened, and endowed with thrust resisting capacity for the pur pose hereinafter more fully explained: The

shank of the thread former ,is held in the punch holder of the press by a horizonta t spring actuated catch 9 seated in a cavity 10 of the holder, and adapted to engage a notch 2 11 in the shank. The spring 12 for actuating the catch is a coiled elastic Wire, compressed to a state of tension by a set screw 13 screwed into the cavity 10 as shown.

The compression die 5 is formed with a Icentral vertical matrix or passage it passing entirely through it and having its cross sectional configuration exactly that ofthe nut blank to be threaded, that is, in the present instance, square. At the upper face of the diev the opening of the passage is of slightly larger area than that of the nut blank to be threaded, being increased just suificiently over the size of the blank to en-.

able the blank to slightly enter it. From said opening the walls of the passage converge downwardly or taper inwardly a certain distance, to the horizontal cross plane 15 shown in Fig. 1. From said cross plane dicularly sided part of the passage is therefore reduced from that ofqpthwpper open- 7 ing for the purpose hereina er stated. The

die bed is also made with a vertical passage 16 through it, somewhat larger than the lower opening of the die proper;

With mechanism constructed ashereinbefore described and shown my improved nut threading process may be. carried out in practical operation as follows: The nutblank 17 having been formed with a central circular perforation 18 as shown in Fig. 4, of a size to freely admit the threaded teat 7 of the thread former, is first placed at the upper opening of the passage 14 of the compression die 5 substantially in the axial line of the thread former and resting on the taper walls of the passage as shown in Fig. 1. Then'with the downward stroke of the press gate the teat of the thread-former will enter the blank until the shoulder 8 engages the upper surface of the blank, after which the continued downward movement of the thread former by the thrust of the shoulder 8 will force the nut blank down through the die. In" such passage through the die the nut blank will be closed in and upset between the converging walls of the passage and compressed upon and around the threads of the thread former, thereby beingshaped thereto, as shown in Fig. 2, and provided with a corresponding internal thread, thus transforming the blank into a finished nut 17 as shown in Fig. 5. After the nut has been forced completely through the die it may be unscrewed from the thread former and the operation repeated.

While the uniform sized and parallel sided part ofthe. passage through the die below the cross plane 15 is of neutral effect respond to the depth of the nut: f

in the positive compression of the nut blank, and therefore .possible of being dispensed with itis nevertheless important to the process, steadying the nut in the final stage of its compression as it is about to leave the tapering part of the passage, and producing a smoother and more uniformly proportioned nut, with straighter and moreparallel sides. The amount of such uniform exten sion of the smallest area of the passage may vary considerably but should preferably cor? In the initial entrance of the thread former into the nut blank, the positioning of the blankwith reference to the die will be insured by the conical point upon theflower= end of the -teat of the thread former,

which will engage the blank and centralize it if the eccentricity is less than the semiternally diameter of the teat. It'will readily be seen that a plurality. of nuts may be threaded by this process at a single operation, by means of proportionate extension of the threaded portion or teat of they thread former. j, Y v i More elaborate and automatic mechanism may be provided for the manufacture of the product on a more extensive scale, but the principles of the process are embodied 1n the appliances shown and will readily be understood without additional illustration;

By the compression of the'material of the nut blank into the s ace around the threads of the thread form r the finished nut will be of reduced size from that of the nut blank, corresponding-to the difference be-' tween the maximum and minimum' cross sectional areas of the matrix of the die, as

indicated by the dotted dimension lines of Figs. 4: and 5. 1 l

In this process as hereinbefore explained, it will be observed that the metal comprising the nut blank ispushed or pressed into the tapering seat of the matrix by the-thrust of the shoulder of the thread former, before which it advances and'that a'compressing strain is therefore imposed uponthe particles of the blank throughout its entire body. This action insures theflow of the metal into the thread grooves of the former, and shapesthe" nut threads accurately and sharply. The shoulder of the thread former in operation prevents the flow or escape of the metalin the direction of the mouth of the die, hence the particles will be compressed into the thread grooves as stated. Mechanism for pulling the nut blank through the die, or the reverse operation of that hereinbefore described will fail of accomplishing this object, and will only draw out, break or attenuate the body of the blank, without tendency to shape the thread thereon. The importance 'of compression therefore as distinguished from tensile strain on the nut blank will be obvious.

I claim as my invention:

1. The herein described process ofthreading nuts consisting essentiallyof pressing the nut blank through a tapering matrix by pressure applied'a'gainst the back or follow ing face of the nut blank as distinguished from its front or leading side in its passage through the die'or matrix and simultaneously carryi'n with it'a screw threaded former within t e'blank, upon and around which the, blank willbe' compressed and inthreaded, substantially as specified.

2. T e herein described process of thread,

.ing nuts consistingessentially of pressing the nut blank through a taperingpassage inga die,-by;;a f0rc1ng' tool engaging the blank and having a -screw threaded former projected within theblank', around and upon which the blankl will' be compressed and shaped, and thereby correspondingly interand upon which the metal Will be comnally threaded, substantially as specified. pressed and shaped and the nut thereby in- 3. The herein-described process of threadternally threaded, substantially as specified.

ing nuts consisting essentially of compress- Signed by me at New Haven, this 8th 5 ing the blank into a tapering matrix by'presday of January, 1912.

sure applied upon the metal mass on the re- ALBERT K LOVELLE treatingside as distinguished from the advancing side, and simultaneously advancing Witnesses: a screw threaded former with the blank, GEORGE L. BARNEs, I

10 Within the perforation thereof, and around ALBERT MOO. MATHEWSON. 

